Just-in-time learning (JITL) has
been widely applied to data-driven
modeling to deal with the nonlinearity problems in industrial processes.
To mitigate the effects of noise existing in JITL, probabilistic JITL
(PJITL) selects samples based on the probability distributions. Considering
the existence of missing data situation, the PJITL algorithm could
also cope with that. However, traditional JITL-based methods, including
PJITL, cannot flexibly select the number of training samples for each
query sample, which would in return influence the accuracy of prediction
for a part of query samples. To solve this problem, we proposed a
method named “variable-scale PJITL” (VS-PJITL) which
can determine the sizes of the local models for each query sample
using a new sample selection criterion. Based on the Euclidean distance,
the sample selection criterion also applies to the variable-scale
JITL (VS-JITL). Then, comparisons of VS-PJITL, PJITL, JITL, and VS-JITL
are tested on a simulated data set and a real industrial data set
from the catalytic naphtha reforming process. By analyzing the two
cases above, VS-PJITL is considered to have superior performance to
the original PJITL (root-mean-square error reduced by 0.3355 and 0.4778).